The invention lies in the field of Optical switchingxe2x80x94Dense Wave Division Multiplexing (DWDM), specifically in the area of operation and provisioning of networks.
One of the major issues in the telecommunications industry today is the ongoing demand for more and more bandwidth. Today, so-called third generation networks employ Wavelength Division Multiplexing technology where both the transmission and the switching of data are in the optical domain. Dense Wavelength Division Multiplexing (DWDM) involves the process of multiplexing many different wavelength signals onto a single fibre. Use of DWDM allows providers to offer services such as e-mail, video, and multimedia carried as Internet Protocol (IP) data over asynchronous transfer mode (ATM) and voice carried over Synchronous Optical NETwork (SONET) (or Synchronous Digital Hierarchy (SDH)). SONET/SDH are defined by a set of related standards for synchronous data transmission over fibre optic networks. The standard for SONET is the United States version and is published by the American National Standards Institute (ANSI). The international version of SDH is the standard published by the International Telecommunications Union (ITU). The differences between SONET and SDH are slight and restricted to the basic frame format.
Despite the fact that these formatsxe2x80x94IP, ATM, and SONET/SDHxe2x80x94provide unique bandwidth management capabilities, all three can be transported over the optical layer using DWDM. This unifying capability allows the service provider the flexibility to respond to differing customer demands over one network.
One property of a DWDM all-optical network is the ability to do wavelength routing. Here, the path of the signal through the network is determined by the wavelength and origin of the signal, as well as the states of the network cross-connects and wavelength changers. Wavelength routing provides a transparent light path between network terminals. A light path is the path that an optical signal traverses in the network from a source to a single destination and may include all-optical wavelength changers.
A property of optical cross-connects is that the optical channels, (also referred to as wavelengths or colours) which are typically fully utilised in carrying data and the related protocols, can be transmitted and inter-connected without knowledge of the data protocol, or even the bit-rate of the data.
There exist cross-connects (including switches, multiplexors, concentrators and interconnects) which need have no knowledge of the data or protocol. These cross-connects act purely at the xe2x80x98physical layerxe2x80x99, the Layer 1 of the International Standards Organisation (ISO) protocol stack. A number of such cross-connects may be co-located to permit higher concentration of traffic thereby taking advantage of the inherent high bandwidth of DWDM transmission systems.
In these existing systems, a separate connection, typically in the form of an Ethernet, is used to carry information between the various system modules and the Operations, Administration, Maintenance, and Provisioning (OAMandP) subsystem. Among other functions, the OAMandP subsystem is responsible for managing the configuring and provisioning of the network and confirming both their correct configuration and ongoing correct operation. In order to carry out part of this function, information regarding configuration is passed to the OAMandP subsystem from the cross-connect (switches, routers and interconnects) controllers and compared with that expected, any differences being indicated to the personnel responsible.
The configuration and provisioning information available from the network is of two types: physical and logical. Typical pieces of information relating to the physical provisioning are the Source and Destination identities of the optical channels. During logical provisioning, the data rate (bit-rate) and protocol are typical of the information made available by the source. This information may be provided to the source directly by some form of call controller associated with the multi-service platform and the other network cross-connects, or from the OAMandP subsystem over the normal OAMandP link.
Currently a significant proportion of optical connections are misconfigured. This leads to extra expense in tracking down and correcting problems as well as potential loss of income. The difficulty in determining that a connection is misrouted has resulted in network providers (or carriers) ordering and installing new equipment rather than risk disrupting live traffic in their attempts to track down misrouted connections. Further, the lack of knowledge of the nature of data being carried has made it difficult and expensive to verify that a connection has been correctly configured.
What is needed is a mechanism to ensure that connections are correctly made during configuration. The need to make these connections less prone to configuring errors becomes especially important where dynamic routing or reconfiguration is being used.
This invention seeks to overcome the problems described above. It achieves this by providing a mechanism to pass connection information regarding a particular path or fibre to the OAMandP subsystem in a manner which eliminates, or at least minimises, the potential for introducing inaccurate information regarding the provisioning of the particular path or fibre. Hitherto, there existed opportunities for error during both physical provisioning (when the various physical units are interconnected with fibre cables) and logical provisioning (when the channels within the various fibres are assigned to carry traffic between customers and the network)
In accordance with an aspect of the present invention, there is provided a control messaging system, which includes; an optical cable which is connected to a multi-service platform (MSP) at one end and is connected to a connecter at the other end; the MSP has a first controller; the connector having a cross-connect and a second controller; within the optical cable, a number of optical fibres being assigned for the transmission of data; at least one of the optical fibres being assigned for use as a provisioning data path; an Operations, Administration. Maintenance and Provisioning (OAMandP) subsystem connected to the provisioning data path through the connector; the first controller signaling a source identity to the OAMandP subsystem over the provisioning data path; and the second controller signaling a destination identity to the OAMandP subsystem from the cross-connect.
In accordance with an aspect of the present invention, there is provided a method of provisioning a system, which includes the steps of; starting a process at a first entry; plugging in an optical cable to a connecter having a cross-connect, viz, the destination. and a multi-service platform, viz, the source; the optical cable having a number of optical fibres assigned for the transmission of data; at least one of said optical fibres being uniquely assigned for use as a provisioning data path; forwarding the destination identity from the cross-connect to an OAMandP subsystem; forwarding the source identity from the multi-service platform to the OAMandP subsystem over the uniquely assigned provisioning data path within the optical cable.
The invention is found in a system comprising switches and cross-connects for optical networks, examples of which are the xe2x80x9cOPTera Connect LX Corexe2x80x9d and the xe2x80x9cOPTera Metro 5200 Multi-service platformxe2x80x9d, both supplied by Nortel Networks.
In the system in which the invention is practised, the shelves and ports of the various units are connected to a central cross-connect system. These connections are assigned unique fibres on the basis of a single colour per fibre, which is directly connected to a particular incoming or outgoing colour on a customer or network fibre. The connections are usually provided as a xe2x80x98transparentxe2x80x99 facility, and the optical bandwidth is in some cases fully used by the data and protocols being carried on a fibre. These facts mean that it is impractical to add any further data to that channel for use in verification of a connection.
The OPTera Metro 5200 supports protocols in native format through a single interface. Once deployed, this interface delivers a particular service and can be altered remotely without hardware changes should an upgrade or other change be required after deployment. Bit-rate independence and protocol independence eliminate the uncertainty associated with forecasting service needs and enables rapid service activation regardless of connection type.
The invention is implemented by including within the prefabricated cables used to interconnect the various system modules, a separate path for the transmission of provisioning data to an Operation, Administration, Maintenance, and Provisioning subsystem (OAMandP). This is referred to as the provisioning data path. When a prefabricated cable is placed in the system during the physical provisioning process, the physical location of both ends of the cable is detected automatically and the information transmitted to the OAMandP subsystem over the provisioning data path to be validated and recorded as necessary. Thus, errors can quickly be identified, and corrections made. Later the same path may be used to transmit data regarding the logical provisioning of the connection, further ensuring the correctness of both the physical and logical connections.
It will be understood by persons skilled in the art that this applies also to duplex operation.
Although this description relates to a system which uses static configuration, the ideas and concepts are equally applicable to a system which uses dynamic, or on-demand, configuration and assignment of fibres and channels.
Other aspects of the invention will be clear on examination of the figures and detailed description following.